The invention relates to an arrangement for visualizing the cores of optical waveguides by employing rod lenses.
One such arrangement is known from DE-OS No. 33 11 472. By that arrangement, the optical waveguide or the fiber preform, for determining the index profile, is illuminated with a diverging bundle of rays which is produced with the aid of a rod lens disposed parallel in relation to the optical waveguide.
For the joining of optical waveguides it is necessary to align them in relation to one another so as to permit a passage of the radiation from one optical waveguide to the other with a low as possible loss. Relative thereto, the optical waveguides which, for example, have a fiber diameter of 125 .mu.m, must be aligned in such a way with one another that the optical axes thereof are in agreement. As a rule, this is effected in that the optical waveguides to be joined are aligned in relation to one another with the aid of a microscope, by observing their outer contours.
In many cases, however, such an alignment is not exactly enough, especially in the case of monomode fibers with which, owning to their smaller core radius, already small deviations of the core center from the fiber center, lead to a relatively high attenuation. An exact alignment of the fiber cores in relation to one another can be effected in that light is permitted to enter into the optical waveguide from its free end, with the light as emerging from the free end of the other optical waveguide being observed. The ends of the two optical waveguides to be joined are then displaced in relation to one another until a maximum light passage is achieved at the joint. This method, however, is circumstantial and requires the two remote ends of the optical waveguides to be accessible.
It is the object of the present invention to provide an optical arrangement for visualizing the cores of optical waveguides, which is of a relatively simple construction and permits the cores of the two optical waveguides to be aligned in relation to one another at the splicing point without the remote ends of the optical waveguides having to be accessible.